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"Think of it this way, the room becomes an integral part of the music in a way that no other amplifier allows." - Bob Carver, on his new Raven 350 tube monoblocks.
Just another gimmick, or..?
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Dynamic loudspeakers and dynamic microphones are very similar devices: A diaphragm, a magnet and a coil. Loudspeaker diaphragms are much larger (and therefore heavier) because they have to move air in order to produce sound, whereas microphone diaphragms are much smaller (and therefore lighter) because they have to respond to small movements of the air. But the basic principle is the same.
Yes, you CAN use a loudspeaker as a microphone. In fact, this has been done for several decades. Remember your school classroom paging/announcement system? Those speakers doubled as microphones for when the Principal wanted to hear what was going on in a classroom. Back in the early '70s, I installed several hundred of them, mostly based on Simplex classroom units and Rauland head-end electronics. The speaker was typically an 8" or so.
You can experiment with this yourself. Just connect a loudspeaker driver to an appropriate preamp and oscilloscope. Speak into the loudspeaker, and see the output on the scope. Voila.
Having established the veracity of using a loudspeaker as a microphone, we can look at other aspects.
Has anyone here ever noticed a change in sound quality of a sound reproduction system when walking around a room? Likely "yes". Where in the room do you find the "best" sound: At your favorite listening position? At some other place in the room or even in another room? Directly in front of the loudspeaker woofer or midrange or tweeter?
Where is the Carver loudspeaker "microphone"? It's at the loudspeaker position.
Is that a good position from which to measure "room sound" to include (delayed) sound in the amplifier output?
Is your loudspeaker a good microphone? After all, it's much larger than a normal microphone.
Are y'all starting to think this through?
:)
There is some well-known science there, along with various claims.
I'll repeat my earlier recommendation: Buy a book on general acoustics - hearing, sound, acoustics.
I LOVE/HATE marketing.
:)
Looks like a few people were fortunate enough to have good luck with Carver, but someone already mentioned the Phase Linear flaming nickname. We also carried Carver very briefly in early 90's, it was brief because we called it the boomerang line because everyone we sold came back, it was get rid of this stuff or go out of business. Where's Carver's products now like the Black Beauty or other very short lived projects Carver has rolled out? So for the fans hope you keep having luck, as for me I'd never touch anything Carver had a hand in.
I've had generally very good luck with Carver. I'm still using the m1.0t amp (the same model used in "the Challenge") to power my front mains in a surround system. It got repaired and returned to factory specs just before the factory closed up shop, and it's run fine ever since. In other words, one repair needed in 30 years.
I use his C-1 preamp for certain things, and it has a fine built-in headphone amp. "Sonic holography" was never my thing; it was a gimmick with odd results.
I had the original model of the Amazing loudspeakers, which imaged very well when set up and placed properly, but with boomy mid-bass; sold them to someone a while ago who still enjoys them. Now those had reliability issues: It's common for the Kapton ribbon to stretch and start to rattle. The Carver factory told me to use a hair dryer to tighten it up, which worked for a while until it didn't. There was a guy who repaired these drivers until he ran out of the needed materials.
That's all fine and dandy, but irrelevant to the topic.
:)
Old thread but probably the "listening to the room" claim is hyperbole. But the SQ of the 350's is incredible. And at 2-3 grand below MSRP (they can be had for that), they are also a bargain. I'll likely be using my Carvers for years after they are no longer available, just like I have with my solid state Edge's.
began in 1973. I purchased a Phase Linear 400 from Leo's Music Collage Ave store to relieve the use of one of my Marantz 8Bs to drive two DIY Lansing reflex/horn cabinets and later two Cerwin-Vega horns for public address use. The groups road dates increased greatly and all the gear took a real beating.
I can't remark on the compared fidelity of the 400 other than to say it never ran out of headroom using efficient horns and sold it in working order almost ten years later. A Series two version was introduced some time in the late seventies.
I didn't know who designed the 400 until I read about the Bob Carver Challenge in an old back issue of an audio periodical. If I'm not mistaken he went on to prove his point successfully.
My primarily analog two channel system evolved and the need for power enough to drive less efficient speakers took me through linear solid state and switching amplifiers. I longed to get back to tubes about the time Bob Carver introduced his Valve Tube Audio 180 and 305 amplifiers.
I was offered an attractive introductory price for a pair of 180s by a dealer that shipped directly from the manufacture in Kentucky. I'm still using them today with a modification to the volume controls and the the 12AX7 and 12AT7 input stage tubes. A 6AL5 tube ensures that the bias voltage remains correct over the entire audio signal cycle which has been referred to as a DC restorer. The amplifiers are push pull parallel KT88 with 2, 4, and 8 ohm output taps. While the tube sockets are plastic they are chassis mounted. There is no printed wire board and all the point to point solder joints still look very good today.
The presentation of these amplifiers can be adjusted slightly by changing the bias voltage from 60 mA to 150 mA and/or by using the feedback switch with approximately 20 dB or about 11 dB of feedback. I've settled on a bias of 98 mA and the higher feedback setting. They receive signal from a battery powered solid state preamplifier and the presentation is dead quiet.
Output tubes need not be matched and are biased as a set. Each tube can be individually measured if one prefers but I have found no real advantage in doing so. The amplifiers run much cooler than other tube amplifiers I've owned.
The photos of the newer 200 and 350 models linked else where seem to be stock photos of the original 180 and 305 models without any marking on the badges.
I read an on line artical were these amplifiers output performance was measured and claimed to be far less than claimed by the manufacture. By comparison a famous 200 watt solid state amplifier I own becomes congested at higher realistic volumes and the Carvers simply loaf along.
I would offer this question: Who were two other highly notable audio designers that played a key roll in the design of the VTA line?
I admire Bob Carver. I use a Sunfire amp. But I'd love to know how an amp can read the room so that feedback can be applied from the room signature. The again even if it's hype the real question is whether it's a good amp which I suspect, given Bob's pedigree, it has a good chance of being.
Is it just me? If he's going to tout the use the KT150, shouldn't the picture he puts out there show KT150's? Sure looks to me like those tubes all say KT88 on them.
If I had an extra 9 or 10 grand kicking around I would try it. Since I don't. I'll wait a few years and see if it all works out.
Seems like he took the long and expensive way around an already solved problem.
...an audio engineering genius.
He was the first to make a high powered solid state amplifier that was listenable in the 1970s, the Phase Linear 700.
I could go on and on but you can Google him to see the other things he's created since then.
The Raven sounds like a very interesting product - the idea of adding some sort of feedback circuitry in a tubed amp to do room correction (if that's what it is) is unique.
Can't wait to read a good review of it used in different rooms.
Far from the first and the 700 was known as the flame 700 as they easily ignited. He quickly learned from that experience that regardless of marketing a unit had to be reliable or bankruptcy was around the corner. He was luckier than many in that regard. Over the years he has been controversial, almost as much as Amar Bose.
Don Brian Levy, J.D.
Toronto ON Canada
Agreed-
I wished that he was still working under Sunfire!
Bob Carver is truly a marketing genius. His ability to take common, mundane, and simple engineering practices and turn them into what appears, to the typical audiophool, as mind bending advances in audio engineering is truly amazing. His use of hyperbole should be studied by every college level marketing student. Even better; Carver should teach the course! He is truly one of the towering geniuses of audio marketing and with this newest hyperbolic display he should get some kind of award for most outragous use of pseudo engineering in a print medium. Well done Bob! This will be a tough act to follow.
> ...with this newest hyperbolic display he should get some kind of award for most outragous use of pseudo engineering in a print medium.>
Sounds like you know what "pseudo engineering" tricks he's employed in the new amp.
Please tell us exactly what he's done, what the effects are and why it's "pseudo engineering".
Thanks.
Perhaps this has replaced his 'DC Restorer' circuit?
I concur and will add that he is certainly an Audio genius as well.
Carver's marketing genius is legendary, I'll agree.
That said, what can you make of the *unique*(?) technology that he's now trying to promote? It is obvious that it has something to do with the use of feedback in his amplifier design, but what might make his use of feedback so extraordinary?
He's probably using the back EMF from the speakers , for a signature for the correction, not a new idea, not sure it works ...
Regards..
Edits: 12/18/14
Say what you will about his marketing he makes damn good products!
I used his gear for 20 years without so much as a hiccup.
I haven't been able to say that about any other gear I have owned.
Probably most of you out there can't say the same about your equipment.
Mr Carver never ceases to amaze me. He could have left this hobby a long time ago...
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